THE AKENE OR ACHEMUM 



121 



IMericarps are of three classes: (I) The Coelospermous, characterized 

 by the possession by the seed of a concave face (Fi^'. '.VA7, a); (2) the 

 Caiiii)yIosi)ernK)iis, characterized by the ])()ssessi()n of a loiigitiuHiially 

 grooved face (Fig. .'i'iS, a); and (3) the Ortliospermous, possessing a 

 plane face (Fig. '.V.]P>). 



The Silicle. (See Sili(nie.) 



The Samara.— All iiulciiiscent fruit witli a winged i)cricarp. "^I'liey 

 are commonly one-seeded, as well as one-carpel led, but may be more. 

 Typically, it is the ovarian wall or the tube of an adnate calyx which 

 develops the wing, but there is no reason why the term should not be 

 extended to include similarly transportable fruits with wings consisting 

 of the accrescent limb of a calyx (Figs. 288 and 289), or corolla (Fig. 291), 

 or a surrounding alate bract (Fig. 292). Commonly the samara possesses 

 but a single wing, unilateral, as in the ash (Fig. 3.')9), or circular, as in 

 the elm (Fig. 287), but not rarely more than one wing is present, as in 

 the maple (Fig. 340), or many Malpighiaceae (Fig. 342). 



—-a 



337 



Kig. 335. Transverse section of an orthosperinous niericarp: 

 pressed mericarp, two of tlu> ribs winged. 337. Coelospermous 

 spermous mericarp of Conium. 



33<S. 



vitta; 6, rib. 330. Dorsall.v o( 

 L-riearp of coriander. 33S. Camp: 



The Utricle (Fig. 341). — A one-seeded indehiscent fruit, the seed 

 enclosed in a thin, bladdery or inflated pericarj). It is commonly one- 

 celled, but occasionally several-celled. Ordinarily, utricles eventually 

 become irregularly rujjtured, l)ut in a few forms there is a regular 

 ventral opein'ng, ap])r()aching toward dehiscence. 



The Akene or Achenium ( Figs. 71 to NO and ;M 1). A small, indehiscent. 

 one-seeded, seed-like fruit, the pci'icnrp soiiicw liat thickened and 

 entirely distinct from the (Miclo.scd seed. The aki-ne varies in many 

 directions toward other fruits. In many cases the pericarp is inclined 

 to be flesln- and in a few it tends toward dehiscence, thus sinuilating a 



